JP2014058055A - Mold release agent for tire inner surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold release agent for a tire inner surface providing sufficient air permeability and durability to a bladder, and further having little omission of a mold release agent component powder from a tire inner surface after molding.SOLUTION: A mold release agent for a tire inner surface contains an inorganic component made by powder, polyether-modified silicone, a surfactant and water, and 25 wt.% or more of the inorganic component is synthetic amorphous silica. The tire is a tire which is obtained by attaching the mold release agent for a tire inner surface to a raw tire and vulcanized.

Description

  The present invention relates to a mold release agent for a tire inner surface. More specifically, the present invention relates to a mold release agent for a tire inner surface that exerts a mold release action by being interposed between a tire and a bladder during tire vulcanization molding.

In the tire manufacturing process, vulcanization molding of an unvulcanized green tire is usually performed by inflating a rubber bag called a bladder with hot water or steam inside the green tire and press-molding the unvulcanized green tire into a mold. Is done by. Usually, in order to perform this process smoothly, a release agent (a release agent for the tire inner surface) is applied in advance to the inner liner surface of the raw tire (hereinafter, the inner surface of the raw tire). The release agent for tire inner surface mainly has the performance to give good lubricity between the inner surface of the raw tire and the bladder (smoothness), and the ability to release the air that has entered the inner surface of the bladder and the raw tire and to bring them into close contact (air) (Permeability) is required, and when the bladder is contracted after the vulcanization is finished, a performance (releasability) that allows the bladder and the inner surface of the green tire to be smoothly peeled off is required. Therefore, a mixed composition of an oil-in-water emulsion of silicones that imparts releasability and a solid particle suspension that imparts smoothness and air permeability is applied as a mold release agent for the tire inner surface. Has been widely practiced.
However, in recent years, due to the diversification of tire products, etc., versatility is required even for raw tires with different shapes, and smooth even when the shape of the bladder and raw tires is not suitable. The need to perform a vulcanization process has arisen. Therefore, air tends to remain between the bladder and the inner surface of the raw tire, and a release agent for the inner surface of the tire that is more excellent in air permeability than before has been demanded. As one of the solutions, natural inorganic minerals such as mica and talc having various particle shapes and a large number of voids between the particles are mixed in the release agent for the tire inner surface.

However, while these natural inorganic minerals impart air permeability, contamination of hard impurities such as quartz is recognized, and they tend to accelerate the deterioration of the bladder surface by causing scratches on the bladder surface. In addition, there has been a problem that these inorganic mineral powders fall off from the inner surface of the molded tire and stain the periphery of the tire.
Patent Document 1 discloses that a composition of an aqueous silicone emulsion and an inorganic powder containing mica having an average primary particle size of 55 to 95 μm is used as a release agent for the tire inner surface. In this example, defects due to lack of smoothness and air permeability during conventional tire molding could be reduced. However, in low profile tires (tires with a flatness ratio of 55 or less) that have been manufactured in recent years, There is a big difference in the shape of the tires, making it difficult to align the air. Moreover, it was not possible to suppress a decrease in bladder life (the number of vulcanizations that can be used before the bladder deteriorates) due to impurities contained in the mica, and powder falling off from the tire inner surface after vulcanization molding.

Patent Document 2 discloses a method in which molding vulcanization is performed by applying a mold release agent composition for tire molding containing room temperature curable silicone rubber, fine particle silicone resin, inorganic powder and a solvent to a bladder. In this method, an improvement in bladder life was observed, but the above-mentioned air permeability could not be improved.
As described above, the conventional release agent for the tire inner surface cannot achieve both sufficient air permeability and durability of the bladder.

JP 2005-193448 A JP-A-5-301229

  The problem to be solved by the present invention is to provide a mold release agent for the tire inner surface which gives sufficient air permeability and durability to the bladder, and further reduces the release of the release agent component powder from the molded tire inner surface. is there.

  As a result of investigations to solve the above-mentioned problems, the present inventors have found that, in a release agent for a tire inner surface, an inorganic component containing a specific amount of synthetic amorphous silica and a polyether-modified silicone are used together. And the present invention has been reached.

The mold release agent for tire inner surface according to the present invention is a mold release agent containing an inorganic component made of powder, a polyether-modified silicone, a surfactant, and water, and is 25% by weight or more of the inorganic component. Is composed of synthetic amorphous silica.
The weight ratio of the inorganic component is 15 to 80% by weight, the weight ratio of the silicone is 10 to 75% by weight, and the weight ratio of the surfactant is 1 to the total amount of the inorganic component, the polyether-modified silicone and the surfactant. It is preferable that it is 10 weight%.

The average particle size (average secondary particle size) of the synthetic amorphous silica powder is preferably 5 to 100 μm.
The tire according to the present invention is a tire obtained by attaching the release agent for the tire inner surface to the inner surface of the raw tire and vulcanizing the tire.

  When the release agent for the tire inner surface of the present invention is used, sufficient air permeability can be imparted, deterioration of the bladder is slow, and durability can be enhanced. Further, the release agent powder does not fall off from the tire inner surface.

  First, each component except the water mix | blended with the mold release agent for tire inner surfaces of this invention is demonstrated, and the mold release agent for tire inner surfaces is explained in full detail.

[Inorganic component consisting of powder]
An inorganic component made of powder (hereinafter sometimes simply referred to as “inorganic component”) is a component mainly used to impart smoothness and air permeability.
The inorganic component includes synthetic amorphous silica. Synthetic amorphous silica has many pores and forms voids in the release agent for the tire inner surface. As a result, air remains between the bladder and the inner surface of the raw tire produced during tire manufacture, and defects due to the fact that the inner surface of the raw tire cannot be partially pressurized without being in close contact with each other can be reduced.

Examples of the synthetic amorphous silica include a wet process amorphous silica obtained by reacting sodium silicate and sulfuric acid, and filtering, washing with water, and drying, vaporizing silicon chloride, Examples include dry process amorphous silica obtained by a gas phase reaction in a hydrogen flame.
Examples of the synthetic amorphous silica include commercially available products such as Nipsil VN3 (manufactured by Tosoh Silica), CARPLEX # 80 (manufactured by EVONIK INDUSTRIES), and WACKER HDK (manufactured by Asahi Kasei Wacker).

In synthetic amorphous silica, primary particle groups having an average particle diameter of several nm to several tens of nm are usually partially chemically bonded to each other to form secondary particles of several μm to several tens of μm. The average particle size (average secondary particle size) of the secondary particles of the synthetic amorphous silica is not particularly limited, but is preferably 5 to 100 μm, more preferably 5 to 30 μm in the measurement result by laser diffraction. ˜20 μm is particularly preferred. When the secondary particle diameter of the synthetic amorphous silica is too small, smoothness is often not obtained. On the other hand, if the secondary particle size of the synthetic amorphous silica is too large, nozzle clogging may occur during spray coating, and a uniform release agent film may not be obtained, resulting in insufficient release properties. .
Synthetic amorphous silica accounts for 25% by weight or more of the inorganic component. The weight ratio of the synthetic amorphous silica in the inorganic component is preferably 50% by weight or more, more preferably 75% by weight or more, and particularly preferably 90% by weight or more. The upper limit of the weight ratio of the synthetic amorphous silica is 100% by weight. If the weight ratio of the synthetic amorphous silica is less than 25% by weight of the inorganic component, sufficient air permeability cannot be obtained.

The inorganic component may contain an inorganic component other than the synthetic amorphous silica (hereinafter may be referred to as “other inorganic component”). Although there is no limitation in particular about the average primary particle diameter of another inorganic component, 1-30 micrometers is preferable and 15-25 micrometers is more preferable. If the average primary particle size of other inorganic components is too small, air permeability may be deteriorated. On the other hand, if the average primary particle size of other inorganic components is too large, nozzle clogging may occur during spray coating. When other inorganic components constitute secondary particles, the average secondary particle diameter of the other inorganic components is also preferably 1 to 30 μm, and more preferably 15 to 25 μm. If the average secondary particle size of other inorganic components is too small, air permeability may be deteriorated. On the other hand, if the average secondary particle size of other inorganic components is too large, nozzle clogging may occur during spray coating. Such other inorganic components are not particularly limited, and examples thereof include synthetic inorganic components other than synthetic amorphous silica, natural inorganic components, and the like. These components may be used alone or in combination of two or more. When there are many natural inorganic minerals contained as other inorganic components, the bladder life may be shortened due to the influence of impurities contained therein.
The synthetic inorganic component other than the synthetic amorphous silica is not particularly limited, and examples thereof include light calcium carbonate, magnesium carbonate, and aluminum silicate. These components may be used alone or in combination of two or more.

The natural inorganic component is not particularly limited, and examples thereof include kaolin, mica (mascobite, sericite), talc, clay, chlorite, bentonite, diatomaceous earth, and heavy calcium carbonate. These natural inorganic components may be used alone or in combination of two or more. The natural inorganic component is preferably at least one selected from mica and talc because it is inexpensive.
The weight ratio of the natural inorganic component to the inorganic component is 75% by weight or less, preferably 50% by weight or less, and more preferably 10% by weight or less. When the weight ratio of the natural inorganic component is more than 75% by weight, the air permeability may not be improved.

[Polyether-modified silicone]
The polyether-modified silicone is a main component that imparts releasability to the release agent for the tire inner surface, and at the same time, a function that prevents the inorganic component from falling off from the tire inner surface. Since the polyether-modified silicone has a hydrophilic group in the molecule, it has a good compatibility with inorganic components such as synthetic amorphous silica, and provides a function (binder effect) for adsorbing particles to adhere to each other. Therefore, the powder falls off from the tire inner surface as compared with the case where other organopolysiloxane emulsion is used.
As the polyether-modified silicone used in the present invention, for example, a polyether-modified silicone in which a polyoxyalkylene group such as a polyoxyethylene group or a polyoxypropylene group is introduced into the side chain of the organopolysiloxane skeleton to make it water-soluble. Can be mentioned. Here, a plurality of polyoxyalkylene groups may be introduced. In that case, the polyoxyalkylene groups may be the same or different. A polyether-modified silicone diluted with an alcohol may be used.

  Examples of the polyether-modified silicone include a modified silicone represented by the following general formula (1). Any of block copolymerization, random copolymerization, alternating copolymerization and the like may be used in the outer parentheses. The polyether-modified silicone may be a modified silicone in which a polyoxyalkylene group is introduced only at one or both ends as shown in the following general formula (2), but the modified silicone shown in the following general formula (1) is more preferable. The hydrophilicity is sufficient and the above-mentioned binder effect is sufficiently obtained.

In the general formula (1), m is an integer of 0 or more and n is an integer of 1 or more. The total number of m and n (m + n) indicates the degree of polymerization of the polysiloxane and is not particularly limited, but is preferably 10 to 700, more preferably 15 to 500, and particularly preferably 20 to 400. When (m + n) is less than 10, sufficient releasability may not be obtained. On the other hand, when (m + n) exceeds 700, the binder effect may not be obtained due to insufficient adsorption to inorganic components such as synthetic amorphous silica.
R represents a polyoxyalkylene group. a is an integer indicating the average number of moles of oxyethylene groups added, and b is an integer indicating the average number of moles of oxypropylene groups added, but either a or b may be 0.

The total number of a and b (a + b) represents the average number of moles added of the oxyalkylene group, means the degree of the length of the polyoxyalkylene group, and is not particularly limited, but is preferably 3-22, More preferably, it is 5-20, and it is most preferable that it is 9-18. When (a + b) is less than 3, water solubility may not be exhibited. On the other hand, when (a + b) exceeds 22, the viscosity may be too high.
R ¹ represents an alkyl group or alkylene group having 2 or more carbon atoms, and R ² represents a hydrogen atom, a methyl group, or an alkyl group or alkylene group having 2 or more carbon atoms. The number of carbon atoms of R ¹ and R ² is not particularly limited, but is preferably 18 or less, more preferably 14 or less, and most preferably 12 or less. When the number of carbon atoms exceeds 18, the binder effect may not be obtained due to insufficient adsorption to inorganic components such as synthetic amorphous silica.

  As the polyether-modified silicone, those having a molecular structure close to a straight chain and exhibiting fluidity in the range from room temperature to 180 ° C. are preferable from the viewpoint of releasability. The viscosity of the polyether-modified silicone is not particularly limited, but from the viewpoint of the balance between releasability and binder effect, the viscosity at 25 ° C. is preferably 10 to 5000 mPa · s, more preferably 100 to 2000 mPa · s. s. If the viscosity is too low, sufficient releasability may not be obtained. On the other hand, if the viscosity is too high, it may not be sufficiently adsorbed by inorganic components such as synthetic amorphous silica and the binder effect may not be obtained.

[Surfactant]
Surfactants not only disperse inorganic components in water, improve the dispersion stability of the release agent for the tire inner surface, but also repel the liquid when applying the release agent for the tire inner surface to the raw tire with a spray device etc. Provides preventing properties (wetting). The wettability can be adjusted by adjusting the blending amount.
The surfactant may be at least one selected from nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants, but has a synergistic dispersion stability and wettability. It is desirable to use two or more of them in combination from the viewpoint of increasing the number of them. In particular, a combined system of a nonionic surfactant and an anionic surfactant is more preferable.

The nonionic surfactant is not particularly limited, but a polyoxyalkylene type such as polyoxyethylene alkyl ether, polyoxypropylene alkyl ether (alkyl may be any one of 1 to 3) is desirable. One or two or more nonionic surfactants may be used in combination.
The anionic surfactant is not particularly limited. For example, carboxylic acid type anionic surfactants, sulfonic acid type anionic surfactants, and the like are suitable. Particularly suitable are group monocarboxylates, polyoxyethylene alkyl ether carboxylates and the like. As the sulfonic acid type anionic surfactant, alkane sulfonate, alkylbenzene sulfonate, dioctyl sulfosuccinate and the like are particularly suitable. These anionic surfactants may be used alone or in combination of two or more.

  When both nonionic surfactants and anionic surfactants are included as surfactants, the weight ratio of each is not particularly limited, but the effect on foaming and the dispersion stability of synthetic amorphous silica powder For reasons of properties, the anionic surfactant / nonionic surfactant (weight ratio) is preferably 65/35 to 99/1, more preferably 70/30 to 98/2, and 80 / It is especially preferable that it is 20-95 / 5.

[Releasing agent for tire inner surface and manufacturing method thereof]
The release agent for the tire inner surface of the present invention is a composition containing the inorganic component, polyether-modified silicone, surfactant and water described above, and is applied between the raw tire and the bladder during tire vulcanization molding. When the bladder expands, it improves lubricity and air permeability, and when the bladder contracts, it works to improve the release properties of both.
The tire inner surface release agent of the present invention is excellent in air permeability because it contains an inorganic component containing synthetic amorphous silica. In addition, since the synthetic amorphous silica is soft, when the release agent for tire inner surface of the present invention is used, there are few scratches on the bladder, and the number of vulcanization (blader life) that the bladder can be used is improved. Due to the binder effect of the polyether-modified silicone on the synthetic amorphous silica, the powder falls off from the tire inner surface.

The weight ratio of the inorganic component, the polyether-modified silicone and the surfactant contained in the release agent for the tire inner surface is not particularly limited, but may be a blending ratio described below.
The weight ratio of the inorganic component is preferably 15 to 80% by weight, more preferably 30 to 75% by weight, particularly preferably 50 to 70% by weight, based on the total amount of the inorganic component, the polyether-modified silicone and the surfactant. It is. When there are too few inorganic components, smoothness may deteriorate. Moreover, when there are too many inorganic components, powder may drop | omit from the molded tire inner surface and a tire storage location periphery may be soiled.

The weight ratio of the polyether-modified silicone is preferably 10 to 75% by weight, more preferably 10 to 50% by weight, and particularly preferably 10 to 20% by weight based on the total amount of the inorganic component, the polyether-modified silicone and the surfactant. % By weight. If the amount of the polyether-modified silicone is too small, the releasability may be deteriorated. Moreover, when there are too many polyether modified silicones, smoothness and air permeability may deteriorate.
The weight ratio of the surfactant is preferably 1 to 10% by weight, more preferably 1 to 7.5% by weight, particularly preferably 2 to 2%, based on the total amount of the inorganic component, the polyether-modified silicone and the surfactant. 5% by weight. If the amount of the surfactant is too small, liquid repellency may occur on the inner surface of the raw tire during application, and the storage stability of the release agent for the inner surface of the tire may deteriorate. Moreover, when there are too many surfactants, the coating defect may generate | occur | produce by the deterioration of smoothness or foaming of the mold release agent for tire inner surfaces.

Although there is no limitation in particular about the weight ratio of water, 75 to 35 weight% of the whole mold release agent for tire inner surfaces is preferable, 70 to 40 weight% is more preferable, 60 to 45 weight% is especially preferable. When the amount of water is large, it takes time to dry the release agent solution for the tire inner surface coated with a sprayer or the like, and the production efficiency deteriorates. On the other hand, if the amount of water is too small, a uniform coated surface cannot be obtained even if a sprayer or the like is used, and a defective tire product may be generated.
The mold release agent for tire inner surface of the present invention may contain additives such as thickeners, antifoaming agents, preservatives and the like as necessary in addition to the components described above.
About the manufacturing method of the mold release agent for tire inner surfaces of the present invention, as long as it includes a step of mixing an inorganic component, a polyether-modified silicone, a surfactant and water, the mixing order and the mixing equipment to be used are particularly limited. There is no.

〔tire〕
The tire of the present invention is a tire obtained by attaching the above-described release agent for the tire inner surface to the inner surface of the raw tire and vulcanizing it.
The tire of the present invention can be manufactured, for example, through an adhesion process and a vulcanization process described below.

(Adhesion process)
In the attaching step, first, a tire original form called a raw tire is prepared by combining and bonding necessary members such as a bead wire and a tire cord mainly with unvulcanized rubber.
Subsequently, the mold release agent for tire inner surfaces of this invention is made to adhere to this raw tire inner surface. As a method for attaching the release agent for the tire inner surface, spraying with an air gun or an airless gun is generally used, but a brush coating or a centrifugal coating machine may be used. The adhesion amount of the release agent for the tire inner surface varies depending on the use and size of the tire product, but is preferably 10 to 50 g / m ² after drying. When the adhesion amount of the release agent for the tire inner surface is small, sufficient release agent performance cannot be obtained. On the other hand, when the adhesion amount is too large, a large amount of the release agent component may fall off and stain the periphery. Thereafter, until the release agent for the tire inner surface attached to the inner surface is sufficiently dried, the raw tire is left for several days if it is several tens of minutes to longer at room temperature.

(Vulcanization process)
Vulcanization is performed as follows on the dry green tire obtained in the adhesion step. First, the raw tire is placed in a metal mold, and a rubber bag called a bladder is pressed at high temperature with steam or the like from the inside to press the raw tire against the mold to obtain the final tire shape and tread. Vulcanize to form a pattern. The bladder surface temperature (mold temperature) during vulcanization is preferably 160 to 190 ° C., the pressure is preferably 1 to 3 MPa, and the vulcanization time is preferably 10 to 60 minutes.
Compared with conventional tires, the tire of the present invention causes less release agent component powder to fall off the molded tire inner surface, suppresses dust scattering around the tire storage area, and prevents operator's hand stains And it is excellent in environmental hygiene.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited to these examples. Hereinafter, “parts” means “parts by weight”.
The “average primary particle diameter” and “average secondary particle diameter” shown below mean 50% cumulative particle diameter (d50) in the volume distribution of the particle diameter measured by the laser diffraction method.

[Example 1]
(Preparation of powder release agent)
Synthetic amorphous silica powder (average secondary particle size: about 17 μm) 51.5 parts, sodium dioctyl sulfosuccinate 5 parts, polyoxyethylene secondary alkyl ether 1.0 part, polyether-modified silicone 1 (viscosity at 25 ° C .: 150 mPa · s, average number of added moles of oxyethylene group introduced into the side chain: 11, 42 parts of R ¹ : CH ₂ , R ² : H in general formula (1), thickener xanthan gum powder (product name KELZAN) 0.5 part was mixed with a Nauta mixer until each component became uniform, and a powder release agent was produced.

(Production of release agent for tire inner surface)
While adding 0.3 part of antifoaming agent (product name FS Antifoam 013A) and 0.2 part of preservative (product name Fineside C-9000) to 69.5 parts of water, stirring with a high-speed shear stirrer Then, 30 parts of the aforementioned powder composition was gradually added. After addition of the entire amount, stirring was performed until the powder release agent disappeared and became a uniform and viscous liquid to prepare a release agent for the tire inner surface.
Using the rubber specimen, the obtained release agent for the tire inner surface was evaluated by the method shown below, and the results are shown in Table 1. The measured releasability was 1.2N at maximum and the smoothness was 2.5N.

(Evaluation using rubber specimen)
The obtained tire inner surface release agent was applied to the widest surface of a 4 cm × 7 cm × 0.2 cm unvulcanized inner liner rubber sheet with a sprayer so that the weight after drying was 15 g / square meter. Next, a bladder rubber sheet of the same size was superposed on this unvulcanized rubber sheet, set on a desktop test press machine, and vulcanized by pressing at 180 ° C. and 20 kg / square centimeter for 20 minutes.

1. Releasability The vulcanized rubber sheet was peeled off at 180 degrees, and the peel load required at that time was measured with a tensile tester to evaluate the releasability. The evaluation criteria for releasability are as follows. In addition, when it has already peeled at the end of vulcanization, a tensile test cannot be performed, but it is evaluated as ◎ because it is excellent in releasability.
A: Peeling with a tensile load of less than 0.5N.
○: Peeling with a tensile load of 0.5N or more and 1.5N or less.
X: Peeling with a tensile load of 1.5 N or more.

2. Smoothness Ladder rubber specimens on the vulcanized inner liner rubber sheet surface are cut into 3cm x 3cm and stacked, and a 500g weight is placed on top to create a vertical load, and the bladder rubber specimens are horizontal at a speed of 100mm / min. Using a tensile and friction tester, the tensile load at that time was measured to evaluate the smoothness. The evaluation criteria for smoothness are as follows.
A: The horizontal tensile load is less than 2.2N.
○: Horizontal tensile load is 2.2N or more and less than 2.7N.
X: The horizontal tensile load is 2.7 N or more.

3. Air permeability The vulcanized inner liner rubber specimen and the bladder rubber specimen were observed, and the air permeability was evaluated by visually observing the appearance defect between the two rubber specimens caused by insufficient air permeability. The evaluation criteria for air permeability are as follows.
A: There is no trace of air remaining.
○: Traces of remaining air can be visually confirmed, but vulcanization is completely performed.
X: Traces of remaining air can be visually confirmed, and there are unvulcanized portions in the portions.

4). Removal of inorganic component The vulcanized inner liner rubber specimen was rubbed strongly with a brush, and the removal of the inorganic component was visually observed and evaluated. The evaluation criteria for the removal of inorganic components are as follows.
A: The inorganic component does not fall off around the rubber specimen and does not adhere to the brush.
○: The inorganic component does not fall off around the rubber specimen, but the inorganic component adheres to the brush.
X: The inorganic component fell off around the rubber specimen, and the inorganic component adhered to the brush.

[Example 2]
In Example 1, 51.5 parts of synthetic amorphous silica (average secondary particle diameter: about 17 μm) was changed to 36.5 parts, and 5 parts of natural mica (average primary particle diameter: 45 μm) was newly added to talc. A powder release agent was prepared in the same manner as in Example 1 except that 10 parts of (average primary particle size: 20 μm) were added, and then a release agent for the tire inner surface was prepared and evaluated. The evaluation results are shown in Table 1. The measured releasability was 1.2N at the maximum and the smoothness was 2.0N.

Example 3
In Example 1, 51.5 parts of synthetic amorphous silica (average secondary particle size: about 17 μm) was changed to 33.5 parts, and the amount of polyether-modified silicone 1 was increased by 18 parts to 60 parts. Except for the above, a powder release agent was prepared in the same manner as in Example 1, and then a release agent for the tire inner surface was prepared and evaluated. The evaluation results are shown in Table 1. In addition, the measured value of releasability was a maximum of 0.4N, and the smoothness was 2.3N.
A tire was manufactured by the method described below using the release agent for the tire inner surface obtained in Example 3, and the inside appearance of the tire and the scratches generated on the bladder surface were evaluated. The results are shown in Table 1. In particular, in Example 3, no defects due to insufficient air permeability were observed in all ten. It was also confirmed that the bladder surface after use was not damaged and was excellent in terms of bladder life.

(Manufacture of tires using a mold release agent for tire inner surfaces)
The release agent for the tire inner surface was applied to the inner surface of 10 195 / 50R16 size raw tires so that the coating amount after drying was 15 g / square meter, and continuous vulcanization molding was performed using the same bladder.

1. Inside view of the tire Evaluation was made by visually observing the inside of the vulcanized tire and the bladder. The evaluation criteria for tire interior are as follows.
A: There is no trace of air remaining.
○: Air remains but vulcanization is performed.
X: There is a trace of air remaining, and the portion is not sufficiently vulcanized.

2. Bladder Scratches Since there are fewer bladder scratches, the bladder life becomes longer, so the scratches on the entire bladder after vulcanization were visually observed and evaluated. The evaluation criteria for bladder scratches are as follows.
A: There is no scratch that can be visually confirmed.
○: There are two or less scratches that can be visually confirmed.
X: Three or more scratches can be visually confirmed.

[Examples 4 to 6]
A tire was manufactured in the same manner as in Example 3 except that the polyether-modified silicone in Example 3 was changed to each of the polyether-modified silicones 2 to 4 shown in Table 1, and the inside appearance of the tire and the scratches generated on the bladder surface Evaluated. The results are shown in Table 1.

Example 7
In Example 2, 36.5 parts of synthetic amorphous silica (average secondary particle size: about 17 μm) was changed to 53.5 parts, and instead of polyether-modified silicone 1, polyether-modified silicone 5 (25 ° C.) was used. Viscosity at: 1400 mPa · s, average added mole number of oxyethylene group introduced into side chain: 7, average added mole number of oxypropylene group: 4, R ¹ in formula (1): CH ₂ , R ² : H ) A release agent for the tire inner surface was prepared and evaluated in the same manner as in Example 2 except that 25 parts were used. The evaluation results are shown in Table 1.

Example 8
In Example 1, 51.5 parts of synthetic amorphous silica (average secondary particle size: about 17 μm) was changed to 19.5 parts, and instead of polyether-modified silicone 1, polyether-modified silicone 6 (25 ° C.) was used. Viscosity: 2200 mPa · s, average added mole number of oxyethylene group introduced into side chain: 11, average added mole number of oxypropylene group: 5, R ¹ in formula (1): CH ₂ , R ² : H ) A tire inner surface release agent was prepared and evaluated in the same manner as in Example 1 except that 74 parts were used. The evaluation results are shown in Table 1.

Example 9
A tire was obtained in the same manner as in Example 3 except that the synthetic amorphous silica (average secondary particle size: about 17 μm) was changed to synthetic amorphous silica (average secondary particle size: about 80 μm) in Example 3. Manufactured and evaluated the internal appearance of the tire and the scratches on the bladder surface. The results are shown in Table 1.

[Comparative Example 1]
(Preparation of powder release agent)
Synthetic amorphous silica powder (average secondary particle size: about 17 μm) 4.5 parts, natural mica (average primary particle size: 45 μm) 20 parts, talc (average primary particle size: 20 μm) 43.0 parts, dioctylsulfosucci 5 parts of sodium acid, 1.0 part of polyoxyethylene secondary alkyl ether, 6 parts of polyether-modified silicone 1 and 0.5 part of thickener xanthan gum powder (product name: KELZAN) are mixed uniformly with a Nauta mixer. It mixed until it was in the state, and produced the powder composition.

(Preparation of release agent solution for tire inner surface)
While adding 0.3 part of antifoaming agent (product name FS Antifoam 013A) and 0.2 part of preservative (product name Fineside C-9000) to 69.5 parts of water, stirring with a high-speed shear stirrer Then, 30 parts of the aforementioned powder composition was gradually added. After the total amount was added, stirring was performed until the powder release agent disappeared and became a uniform viscous liquid, to prepare a release agent for the tire inner surface.
The obtained release agent for the tire inner surface was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1. The measured releasability was a maximum of 1.8 N and the smoothness was 1.8 N. However, the air permeability was poor, and the appearance was poor due to the air remaining in part between the two specimens. Admitted.
Further, using the obtained release agent for the tire inner surface, a tire was produced in the same manner as in Example 3, and the inside appearance of the tire and the scratches generated on the bladder surface were evaluated. The results are shown in Table 1. Appearance defects due to insufficient air permeability were observed on the inner surfaces of all 10 completed tires. In addition, on the inner surface of the bladder used, some of the scratches caused by hard particles thought to have been contained in talc or mica were found.

[Comparative Example 2]
(Preparation of release agent solution for tire inner surface)
To 89 parts of polyether-modified silicone 1, 4.5 parts of synthetic amorphous silica powder (average secondary particle size: about 17 μm), 5 parts of sodium dioctylsulfosuccinate, 1.0 part of polyoxyethylene secondary alkyl ether, increased 0.5 part of a sticky xanthan gum powder (product name KELZAN) was added and stirred with a high-speed shear stirrer until uniform, to prepare a release agent for the tire inner surface.
The obtained release agent for the tire inner surface was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1. In addition, although the measured value of releasability was 0.3N at the maximum, smoothness was 2.8N and was inferior. The air permeability was poor, and an appearance defect due to air remaining in a part between the two specimens was recognized. Even when the vulcanized inner liner rubber specimen was strongly rubbed with a brush, there was little dropout of inorganic components.
Further, using the obtained release agent for the tire inner surface, a tire was produced in the same manner as in Example 3, and the inside appearance of the tire and the scratches generated on the bladder surface were evaluated. The results are shown in Table 1. Although no scratch was observed on the inner surface of the bladder used, wrinkles due to insufficient smoothness and poor appearance due to insufficient air permeability were observed on all ten tire inner surfaces. There was little dropout of inorganic components from the tire inner surface.

Claims (4)

  A release agent containing an inorganic component made of powder, a polyether-modified silicone, a surfactant, and water, wherein 25% by weight or more of the inorganic component is a synthetic amorphous silica. Release agent.   The weight ratio of the inorganic component is 15 to 80% by weight, the weight ratio of the polyether modified silicone is 10 to 75% by weight, and the weight of the surfactant with respect to the total amount of the inorganic component, the polyether-modified silicone and the surfactant. The mold release agent for tire inner surfaces of Claim 1 whose ratio is 1 to 10 weight%.   The mold release agent for tire inner surfaces of Claim 1 or 2 whose average particle diameter (average secondary particle diameter) of the said synthetic amorphous silica is 5-100 micrometers.   A tire obtained by adhering a release agent for a tire inner surface according to any one of claims 1 to 3 to an inner surface of a raw tire and vulcanizing the tire.